ISSN:0730-7268    

DOI:10.1002/etc.5620040601

出版商:Wiley Periodicals, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractA plume of contaminated groundwater originating from an abandoned disposal pit for wood‐creosoting waste was characterized. The important organic contaminants in the plume include naphthalene, 1‐methylnaphthalene, 2‐methylnaphthalene, dibenzofuran and fluorene at individual concentrations of 1,000 to 100 μg/L. Core material from the site was studied to determine if organisms in the subsurface could adapt to this waste and if biological activity influenced the disposition of the plume. Biodegradation of these organic pollutants in subsurface material from the margin of the plume was rapid. No biodegradation of the pollutants was detected in pristine subsurface material from the same geological structure. As a result of this adaptation, the disposition of the plume was not controlled by the rate of utilization of the pollutants by the microorganisms but by the extent of utilization allowed by the supply of

ISSN:0730-7268    

DOI:10.1002/etc.5620040602

出版商:Wiley Periodicals, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractStudies were conducted to characterize the aerobic and anaerobic microbial activities in surface and subsurface soils of septic tank tile fields. Under aerobic conditions, the indigenous microflora in the soils degraded the natural substrates and many of the synthetic chemicals tested. Half‐lives (t1/2) for the biodegradation (14CO2production) of glucose and glutamic acid ranged from 2 to 5 h in surface soils and from 8 to 25 h in subsurface soils. Degradation of stearic acid was slower in both surface (t1/2= 118 h) and subsurface (t1/2= 82 to 312 h) soils.14CO2evolution from the synthetic chemicals methyl parathion and 2,4‐D was more variable than that from the natural substrates and occurred in the surface soil but in only one of the two subsurface soils tested. The aerobic biodegradation of nitrilotriacetate (NTA) was studied only in the two subsurface soils from the tile fields. NTA was mineralized in both soils and the half‐life for14CO2production ranged from 86 to 161 h. When the surface and subsurface soils were incubated under anaerobic (nitrate‐reducing) conditions, active denitrification by the indigenous microflora was observed. In surface soils, denitrification occurred immediately after an anaerobic preincubation (12 to 24 h) and the N2O production curve was linear. In subsurface soils, N2O production occurred only after 32 to 44 h of anaerobic incubation and was described by an S‐shaped curve. Biodegradation of the natural substrates (glucose, glutamic and acetic acid) under these anaerobic conditions ranged from 1 to 2 h for the surface soil to 2 to 20 h for subsurface soils. The half‐life for the anaerobic mineralization of NTA ranged from 49 to 125 h in the subsurface soils. The results indicate that the indigenous microflora in the subsurface have lower activities than do those in surface soils; however, the subsurface microflora can effectively mineralize natural and certain synthetic substrates under aerobic and denitrifying

ISSN:0730-7268    

DOI:10.1002/etc.5620040603

出版商:Wiley Periodicals, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe presence of trichloromethane and volatile chlorinated ethene compounds in local groundwater, where no use of these compounds could be determined, prompted a search for their source using models of the aquifer in the laboratory. Preliminary work indicated that chloroethene andcis‐ andtrans‐1,2‐dichloroethene resulted from subsurface transformation of spilled tetra‐ and trichloroethene, which are commonly used as industrial degreasers. This study was undertaken to determine the interactions and subsurface factors, including the microbiota and commonly used chlorinated organic solvents, which brought about these transformations.Static microcosms containing groundwater and sediments were spiked with four organic solvents (tetrachloroethene, trichloroethene, 1,1,1‐trichloroethane, and tetrachloromethane) and analyzed by GC at intervals during a 16‐week incubation period. Eh and pH were determined concurrently.The environmental conditions within the microcosms, i.e., neutral to acid pH and reductive potential, indicated that reductive dehalogenation was the pathway by which the observed products were formed. An aqueous milieu and the presence of electron donors and microbial mediators are believed to be influential factors. Evidently, one carbon‐halogen bond in each of the solvents was ruptured to yield a compound with one fewer chlorine than its precursor. The products of transformations in microcosms were exotic compounds also found in the groundwater. They were formed only in microcosms from which living microorganisms

ISSN:0730-7268    

DOI:10.1002/etc.5620040604

出版商:Wiley Periodicals, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractContamination of aquifers is a serious threat to groundwater supplies. Once an aquifer is contaminated, it may remain so for many years. Biological methods for restoring aquifers polluted by organic compounds offer a promising solution. Techniques such as in situ treatment by stimulating the indigenous microbial population or withdrawal of the contaminated groundwater and treatment by conventional wastewater treatment processes have been used successfully. Mutant and acclimated microorganisms can be used in these systems in attempts to increase the rate of degradation of recalcitrant compounds. Stimulation of the indigenous microbial population by the addition of oxygen and nutrients has been shown to be effective in the removal of petroleum products, iron and manganese, and organic solvents. Acclimated and mutant strains of bacteria have been inoculated into treatment reactors and into soil to degrade various organic chemicals. Polluted groundwater also has been withdrawn and treated by activated sludge processes. While some of these processes have not been adequately tested under field conditions and may be limited in applicability, biological methods are effective in restoring some contaminated aquifers.

ISSN:0730-7268    

DOI:10.1002/etc.5620040605

出版商:Wiley Periodicals, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe metabolism of phenol and various chlorophenols was studied in groundwater aquifer microcosms. Flow‐through column microcosms containing pristine aquifer material were used to assess aerobic biodegradation processes. Reductive metabolism of the substrates was studied in serum bottles filled with aquifer material contaminated by municipal landfill leachate. We found that microorganisms present in an actively methanogenic aquifer were able to metabolize chlorophenols by replacing the halogen substituents with hydrogen atoms. The identity of the dehalogenated intermediates was confirmed by mass spectrometry for a model substrate and by cochromatography for others. Complete removal of the aryl halides was necessary before the phenol intermediate could be mineralized to methane and carbon dioxide. However, the chlorophenols tended to persist in anoxic microcosms containing material from the same aquifer but from a non‐methanogenic site. Metabolism and acclimation of chlorophenols and phenol was noted in aerobic microcosm studies, but the degradation pathway(s) were not establis

ISSN:0730-7268    

DOI:10.1002/etc.5620040606

出版商:Wiley Periodicals, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe number and metabolic diversity of bacteria were studied in groundwaters collected in the United States and Canada. Bacterial numbers were determined by acridine orange direct counts, viable plate counts and14C most‐probable‐number counts. Metabolic diversity was determined by heterotrophic activity and biodegradation potential assays using several classes of natural and xenobiotic substrates. Rates of metabolism in diversity studies (uptake and/or mineralization to carbon dioxide) were measured by radiotracer techniques and rate data were analyzed by nonlinear regression models to generate appropriate kinetic constants. Overall, the density and activity of groundwater bacteria were comparable to values reported for oligotrophic marine and freshwater systems. Bacterial numbers ranged from approximately 102to 106cells/ml, depending on the enumeration technique used and the particular sample tested. Turnover times for natural compounds in heterotrophic activity assays (i.e., glucose, amino acids) ranged from less than 100 to more than 2,000 h. Degradation half‐lives for xenobiotic and natural substrates in biodegradation potential studies exhibited a comparable range of values. In general, our results indicate that groundwater bacteria have the potential to metabolize several classes of natural and xenobiotic substrates, although at reduced rates compared with those of surface water sy

ISSN:0730-7268    

DOI:10.1002/etc.5620040607

出版商:Wiley Periodicals, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractAfter exposure to sunlight or laboratory UV light, sterilized water samples (or their reconstituted concentrates) from California and Hawaii oxidized several common environmental contaminants, including ethylenethiourea, thiobencarb, DDE and aldrin, which do not absorb ultraviolet radiation appreciably in the sunlight wavelength region. Unirradiated controls were inactive. The generated oxidant remained active in the water samples for at least 60 min in the dark at ambient temperature. Tryptophan and tyrosine were isolated as causative agents but were not the actual oxidants. Such light‐induced degradation reactions have important implications for the environmental fate of chemicals in water and for environmental modellin

ISSN:0730-7268    

DOI:10.1002/etc.5620040608

出版商:Wiley Periodicals, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe uptake and depuration rate constants for [14C]2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (14C‐TCDD) in growing rainbow trout were obtained in a laboratory experiment involving a 6‐h static water uptake exposure at 107 ng/L (ppt) followed by a 139‐d flow‐through depuration period. Improved mathematics were developed for estimating uptake and depuration rate constants and an equilibrium bioconcentration constant that accounts for growth dilution of the total chemical body burden. The uptake and depuration rate constants (k1' andk2) for14C‐TCDD in rainbow trout (whole fish) were determined to be 108 ± 3 ml water/g whole fish/d and 0.012 ± 0.001 d−1, respectively. Based on these data, the equilibrium bioconcentration constant for TCDD, defined as the ratio of uptake to depuration rate constants, was 9,270 ± 1,050, and the elimination half‐life,t1/2, of the total body burden was 58 ± 5 d. Clinical observations of the fish concurred with those previously report

ISSN:0730-7268    

DOI:10.1002/etc.5620040609

出版商:Wiley Periodicals, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractLeucine aminonaphthylamidase (LAN) is a lysosomal enzyme that appears in blood plasma after cell death. Levels of plasma LAN (PLAN) were assayed to quantify toxicant stress in rainbow trout in a series of experiments. Blood samples were taken from groups of fish weighing 80 to 100 g following intraperitoneal (i.p.) and/or waterborne exposure top‐methylphenol (PMP) or carbon tetrachloride (CCl4).The duration of postinjection holding significantly affected PLAN activity in control and PMP‐dosed rainbow trout; the largest increases occurred after 96 h. There were significant correlations between dose and PLAN activity after both PMP and CCl4injection. PLAN levels of fish injected with PMP at doses of 0.075 to 0.75 of the 96‐h i.p. LD50 were elevated by 27 to 63% relative to controls 96 h after injection. PLAN levels of fish injected with CCl4at doses of 0.18 to 0.79 of the i.p. LD50 were elevated by 38 to 135% relative to controls 48 h after injection. Exposure of fish to a waterborne concentration of 0.028 mM PMP (0.41 96‐h LC50) significantly increased PLAN activity after 48, 96 and 192 h; activities increased by 38 to 87% relative to controls. Elevated PLAN activity was strongly correlated with decreased plasma protein levels. The temperature and duration of plasma storage affected the measured PLAN activity of control and PMP‐dosed rainbow trout. While diet modified PLAN activity, the gender of immature fish had no effect.Hepatic lesions visible by light microscope were observed with waterborne PMP exposure; parenchymatous edema was closely associated with increased liver somatic index. There were, however, no visible lesions or changes in the index associated with the pulse i.p. doses of PMP and CCl4. In these cases, biochemical lesions preceded any evidence of histo

ISSN:0730-7268    

DOI:10.1002/etc.5620040610

出版商:Wiley Periodicals, Inc.    

年代:1985

数据来源: WILEY